diff --git a/src/pykalmanfilter/CMakeLists.txt b/src/pykalmanfilter/CMakeLists.txt
index 9fd9178c..f551c368 100644
--- a/src/pykalmanfilter/CMakeLists.txt
+++ b/src/pykalmanfilter/CMakeLists.txt
@@ -5,6 +5,7 @@ set(SELF_SRCS pykalmanfilter.cpp)
 
 xo_pybind11_library(${SELF_LIB} ${PROJECT_NAME}Targets ${SELF_SRCS})
 xo_pybind11_dependency(${SELF_LIB} xo_kalmanfilter)
+xo_pybind11_header_dependency(${SELF_LIB} pyreactor)
 xo_pybind11_dependency(${SELF_LIB} xo_pyutil)
 
 # cmake config generated by xo-kalman filter
@@ -23,11 +24,14 @@ xo_pybind11_dependency(${SELF_LIB} xo_pyutil)
 #       ..
 #       INTERFACE_LINK_LIBRARIES "reactor;Eigen3::Eigen")
 #
-# (B) target_link_libraries() below; via the original
-#     xo_external_target_dependency
+# (B) xo_external_target_dependency
 #       (xo_kalmanfilter Eigen3 Eigen3::Eigen)
-#     in xo-kalmanfilter/src/kalmanfilter/CMakeLists.txt
+#     below
 #
-target_link_libraries(${SELF_LIB} PUBLIC Eigen3::Eigen)
+#     reminder XO_SUBMODULE_BUILD relies on
+#              xo_external_target_dependency() calling find_package()
+#
+xo_external_target_dependency(${SELF_LIB} Eigen3 Eigen3::Eigen)
+#target_link_libraries(${SELF_LIB} PUBLIC Eigen3::Eigen)
 
 # CMakeLists.txt